Malaysian Patent Application No. PI 2012002321 filed by the Applicant discloses an apparatus and method for testing of semiconductor components using turret machine and more particularly the apparatus involves the use of a linear motor with mechanical pushers to control the vertical motion of the pickup heads.
The apparatus of this prior art has a continuous delivery system in which the base machine consists of a turret system with 32 pickup heads that is capable of rotating in a circular motion in order to perform different tests in one cycle. The advantage of the apparatus of this prior art invention is that the machine is capable of picking up and processes two types of semiconductor components simultaneously or alternatively doubles the amount of the same semiconductor components being processed.
One end of each of said mechanical pushers is attached to a rim on said base machine. The vertical movement of said rim is powered by a linear motor. As all said mechanical pushers are attached to said rim, all said mechanical pushers move in unison.
Taking the use of the apparatus of this prior art for testing of semiconductor components as an example, during operation, the pick up head, which picked up and carry the semiconductor test component, is pressed against a printed circuit board at a test station with a downward force of a predetermined magnitude by a vertically descending mechanical pusher. A certain amount of force is needed so that the test semiconductor component gets a good contact with the printed circuit board. However, the semiconductor test component or the printed circuit board may break if an excessive amount of force is applied. The force that is exerted on the printed circuit board is dependent on the linear motor and a spring in the mechanical pusher. This threshold force differs for different semiconductor components so that when different types of semiconductor components are tested, several parameters need to be varied and recalibrated including the range of displacement of said mechanical pushers. This results in unproductive change over time.
On top of that, there is an upper limit on the force that can be applied. The apparatus of this prior art needs to be enhanced with additional feature should a greater amount of force is needed. Furthermore, as all the pushers are being attached to a rim, all the pushers move in unison in a vertical direction and the force exerted on any of the pick up head is the same and limited to only one force magnitude at one time. This is undesirable when different level of force is required to be applied on the components for carrying out different tests simultaneously in one test cycle.
Another drawback to the tester using mechanical pushers is that there is a limitation on the speed of the pushers. At higher speed, the linear motor and the mechanical pushers require more load. However, this will result in an increase in unwanted heat and noise, which is not favourable.
As the thickness of wafers and semiconductor components are getting ever thinner, the preciseness of the reach of the pick up heads or the pressing force of pick up heads on the target objects can greatly influence the yield and through put of a production process. The use of linear motor to control the motion of the pushers, and thus the pick up heads, does not have the preciseness, speed and flexibility required in handling simultaneously multi semiconductor components or wafers in a production process. Similarly, in situation where more delicate pressure and preciseness in reach to the target objects are required, such as very pressure sensitive ultra thin target objects, a linear motor control system is no longer adequate.
In view of these and other shortcomings of the existing art, it would be useful and advantageous to provide an apparatus that can controls the movement of said pickup heads independently of each other, yet, able to apply different force magnitudes on each pick up heads respectively.
It is another objective of the present invention to provide an apparatus that requires simple calibration which takes minimal time, when different force is needed to be applied on the test components.
It is yet another objective of the present invention to provide an apparatus which is able to support higher limit on the pressing force magnitude on the test components.
It is yet another objective of the present invention to provide an apparatus which can operate at faster speed, which allow higher productivity due to reduced change over time and higher throughput.
It is yet a further objective of the present invention to provide an apparatus adapted to pick, place and/or press on a very thin, delicate wafer or semiconductor components with great preciseness so as to reduce breakage considerably.